U.S. Pat. No. 4,626,434, assigned to Rich Products, relates to a single step process for infusing fruit. In this process the fruit is placed into a 70% fructose syrup bath maintained at a temperature of approximately 65-71.degree. C. (150-160.degree. F.). (It is possible to use sucrose, which is a disaccharide consisting of fructose and glucose chemically bonded together. During processing the sucrose will be "inverted", i.e., the bond will be shattered and the sucrose will end up as fructose and glucose.) In the sugar syrup bath a portion of the fruit juice (water and aromatics) within the fruit will pass through the outer membranes of the fruit osmotically, and as the water tends to dilute the sugar syrup, the sugar syrup will be maintained at or near its initial sugar percentage by introducing concentrated sugar syrups. During this time equal amounts of diluted syrup are withdrawn and subsequently treated, the final byproduct being a sugar syrup which is reintroduced into the bath. The disadvantage of the Rich Products process is that the water goes out of the fruit faster than the sugar goes in, causing osmotic dehydration of the fruit. Once the fruit is osmotically dehydrated, it cannot be "plumped up," i.e., re-infused with a plumping liquid so that it does not appear to be dehydrated. In addition, there are no juice by-products. The juice is irretrievably mixed with the syrup.
U.S. Pat. No. 5,320,861, assigned to Ocean Spray, discloses a two step process for infusing fruit. In the first step a decharacterized fruit product is produced by a countercurrent "leaching" process. In the countercurrent process up to 94% of the fruit juice content is extracted and is replaced by water. This process does not cause osmotic dehydration as the osmotic transfer rates of the water and fruit juices are substantially the same. The decharacterized fruit is substantially nothing more than cellulose and water. The byproduct of this process is 3% fruit juice, which can be changed by evaporation to 8%. The second step of the process also uses a countercurrent process, the apparatus being substantially identical to that used in the first step of the process. During the second step an aqueous blend (or liquor) of sucrose and cranberry fruit juice components (or other equivalent fruit components) is used to infuse the decharacterized fruit. In addition, fruit flavorings and food colorings must be added to the infusing liquor used in the second step of the process in order to make the infused fruit resemble a cranberry. The result is a new fruit product in the way of infused cranberry having the sweetened flavor of the infusing liquor and cranberry juice. The resultant fruit product is dried and optimally has a sugar to water by weight ratio of about 70%. This sugar to water weight ratio is commonly referred to as Brix in the industry, and this term will be used in the remained of this specification. The disadvantage of this process is that the augers used by the countercurrent process is rough on soft or fragile fruit, causing too many undesirable fines. In addition, as water is extracted from the cranberries during the second step, the water will dilute the infusing liquor, and the augers cause mixing of dilute infusing liquor with the initial concentrated infusing liquor.
U.S. Pat. No. 2,785,071 to Mathews teaches infusing previously extracted fruit by moving a sugar front through the previously extracted fruit, the front having a sugar content beginning at zero and increasing in sugar content as the front is passed by the layers of fruit. In order to properly infuse the fruit according to the Mathews patent, a pretreatment process must be followed to prepare the fruit for infusing. The fruit must be soaked in a solution bath of 1/4 to 1% of sulfur dioxide brine. The brine acts as a preservative for the fruit. Next, the fruit is boiled in order to volatilize the sulfur dioxide from the fruit. Boiling also cooks the fruit, tenderizes the fruit, and loosens the fibrous material. The fruit is next washed, diced, and washed again. The fruit now needs to be dyed in order to have any color. The infusion portion of the process disclosed in Mathews is a sequential batch process and is illustrated best in FIG. 1 of the Mathews patent. In the infusion process tanks 6, 7, & 8 are filled with the fruit to be processed, and a front of sugar heated to 49-60.degree. C. (120-140.degree. F.) is initially introduced into the base of tank 6, the sugar initially having a high sugar content. As the front of sugar syrup moves up though tank 6, it will be diluted by the water in the fruit cells of the fruit within the tank in a manner similar to that disclosed in the Rich patent. As the sugar front initially passes through conduit 21 it will have only a slightly higher sugar percentage than that of the fruit through which it has passed. (The initial tank will have fruit which suffers from osmotic dehydration.) As the front of sugar moves up through tank 7 the succeeding fronts of sugar increase in Brix content, and the fruit product will be sweetened. The Mathews patent sweetens the fruit to 77 Brix. A disadvantage of the process is in the pretreatment necessary to prepare it for impregnation with syrup. Thus the fruit is boiled and washed several times, which ruins the flavor of the fruit. In addition, the high temperatures recommended for both pretreatment and infusing turn the fruit mushy and will discolor some fruits, such as cranberries and strawberries. Furthermore, since virtually all the juice of the fruit is washed out during pretreatment, there is no possibility of extracting fruit juice. In addition, this process is not feasible for soft, previously frozen fruit.